Glucokinase (GK) is one of four hexokinases found in mammals [Colowick, S. P., in The Enzymes, Vol. 9 (P. Boyer, ed.) Academic Press, New York, N.Y., pages 1-48, 1973]. The hexokinases catalyze the first step in the metabolism of glucose, i.e., the conversion of glucose to glucose-6-phosphate. Glucokinase has a limited cellular distribution, being found principally in pancreatic xcex2-cells and liver parenchymal cells. In addition, GK is a rate-controlling enzyme for glucose metabolism in these two cell types that are known to play critical roles in whole-body glucose homeostasis [Chipkin, S. R., Kelly, K. L., and Ruderman, N. B. in Joslin""s Diabetes (C. R. Khan and G. C. Wier, eds.), Lea and Febiger, Philadelphia, Pa., pages 97-115, 1994]. The concentration of glucose at which GK demonstrates half-maximal activity is approximately 8 mM. The other three hexokinases are saturated with glucose at much lower concentrations ( less than 1 mM). Therefore, the flux of glucose through the GK pathway rises as the concentration of glucose in the blood increases from fasting (5 mM) to postprandial (≈10-15 mM) levels following a carbohydrate-containing meal [Printz, R. G., Magnuson, M. A., and Granner, D. K. in Ann. Rev. Nutrition Vol. 13 (R. E. Olson, D. M. Bier, and D. B. McCormick, eds.), Annual Review, Inc., Palo Alto, Calif., pages 463-496, 1993]. These findings contributed over a decade ago to the hypothesis that GK functions as a glucose sensor in xcex2-cells and hepatocytes (Meglasson, M. D. and Matschinsky, F. M. Amer. J. Physiol. 246, E1-E13, 1984). In recent years, studies in transgenic animals have confirmed that GK does indeed play a critical role in whole-body glucose homeostasis. Animals that do not express GK die within days of birth with severe diabetes while animals overexpressing GK have improved glucose tolerance (Grupe, A., Hultgren, B., Ryan, A. et al., Cell 83, 69-78, 1995; Ferrie, T., Riu, E., Bosch, F. et al., FASEB J., 10, 1213-1218, 1996). An increase in glucose exposure is coupled through GK in p-cells to increased insulin secretion and in hepatocytes to increased glycogen deposition and perhaps decreased glucose production.
The finding that type II maturity-onset diabetes of the young (MODY-2) is caused by loss of function mutations in the GK gene suggests that GK also functions as a glucose sensor in humans (Liang, Y., Kesavan, P., Wang, L. et al., Biochem. J. 309, 167-173, 1995). Additional evidence supporting an important role for GK in the regulation of glucose metabolism in humans was provided by the identification of patients that express a mutant form of GK with increased enzymatic activity. These patients exhibit a fasting hypoglycemia associated with an inappropriately elevated level of plasma insulin (Glaser, B., Kesavan, P., Heyman, M. et al., New England J .Med. 338, 226-230, 1998). While mutations of the GK gene are not found in the majority of patients with type II diabetes, compounds that activate GK and, thereby, increase the sensitivity of the GK sensor system will still be useful in the treatment of the hyperglycemia characteristic of all type II diabetes. Glucokinase activators will increase the flux of glucose metabolism in xcex2-cells and hepatocytes, which will be coupled to increased insulin secretion. Such agents would be useful for treating type II diabetes.
This invention provides a compound, comprising an amide of the formula: 
wherein R is hydrogen, lower alkyl, hydroxy lower alkyl, lower alkoxy lower alkyl, 
an unsubstituted or hydroxy substituted cycloalkyl ring containing 5 or 6 ring carbon atoms, a five- or six-membered saturated heterocyclic ring, which contains from 1 to 3 hetero ring atoms selected from the group consisting of sulfur, oxygen or nitrogen, or an unsubstituted five- or six-membered heteroaromatic ring, connected by a ring carbon atom, which contains from 1 to 3 heteroatoms in the ring selected from the group consisting of sulfur, nitrogen and oxygen; R3 is cycloalkyl having 3 to 7 carbon atoms; R4 is an unsubstituted or mono-substituted five- or six-membered heteroaromatic ring, connected by a ring carbon atom to the amine group shown, which five- or six-membered heteroaromatic ring contains from 1 to 3 heteroatoms selected from sulfur, oxygen or nitrogen, with one heteroatom being nitrogen adjacent to the connecting ring carbon atom; said mono-substituted heteroaromatic ring being monosubstituted at a position on a ring carbon atom other than adjacent to said connecting carbon atom with a substituent selected from the group consisting of lower alkyl, halo, nitro, cyano,
xe2x80x94(CH2)mxe2x80x94OR6, 
xe2x80x94(CH2)mxe2x80x94NHR6;
n is an integer from 0 to 2;
m is 0, 1, 2, 3 or 4;
R1, R2, R6, R7 and R8 are independently hydrogen or lower alkyl and * designates the assymetric carbon atom center;
or a pharmaceutically acceptable salt thereof.
The compounds of formula I have been found to activate glucokinase in vitro. Glucokinase activators are useful for increasing insulin secretion in the treatment of type II diabetes in humans.
This invention provides a compound, comprising an amide of the formula: 
In the compound of formula I, the xe2x80x9c*xe2x80x9d designates the asymmetric carbon atom in this compound with the R optical configuration being preferred. The compound of formula I may be present in the pure R form or as a racemic or other mixtures of compounds of formula I having the R and S optical configuration at the asymmetric carbon shown. The pure R enantiomers are preferred.
As used throughout this application, the term xe2x80x9clower alkylxe2x80x9d includes both straight chain and branched chain alkyl groups having from 1 to 7 carbon atoms, such as methyl, ethyl, propyl, isopropyl, preferably methyl and ethyl. As used herein, the term xe2x80x9chalogen or haloxe2x80x9d unless otherwise stated, designates all four halogens, i.e. fluorine, chlorine, bromine and iodine.
The term xe2x80x9chydroxy lower alkylxe2x80x9d includes any hydroxy lower alkyl group where lower alkyl is defined as above. The hydroxy can be substituted at any place on the lower alkyl group such as 1-hydroxy ethyl, 2-hydroxy propyl, or 2-hydroxy isopropyl. Lower alkoxy lower alkyl denotes any hydroxy lower alkyl group wherein the hydrogen of the hydroxy moiety is substituted by lower alkyl. The cycloalkyl groups, unless otherwise designated, are those compounds having a ring of from 3 to 7 carbon atoms, particularly cyclopentyl, cyclohexyl, cyclobutyl and cyclopropyl. The preferable cycloalkyl groups contain from 5 to 6 ring carbon atoms.
R can be any five- or six-membered saturated heterocyclic ring containing from 1 to 3, preferably from 1 to 2, heteroatoms selected from the group consisting of sulfur, oxygen or nitrogen. Any such five- or six-membered saturated heterocyclic ring can be used in accordance with this invention. Among the preferred rings are morpholinyl, pyrrolidinyl, piperazinyl, piperidinyl, etc.
As used herein, the term xe2x80x9clower alkanoic acidxe2x80x9d denotes lower alkanoic acids containing from 2 to 7 carbon atoms such as propionic acid, acetic acid and the like. The term xe2x80x9clower alkanoylxe2x80x9d denotes monovalent alkanoyl groups having from 2 to 7 carbon atoms such as propionoyl, acetyl and the like. The term xe2x80x9caroic acidsxe2x80x9d denotes aryl alkanoic acids where aryl is as defined above and alkanoic contains from 1 to 6 carbon atoms. The term xe2x80x9caroylxe2x80x9d denotes aroic acids wherein aryl is any aromatic hydrocarbon containing 6 or 12 carbon atoms, preferably phenyl, and the aroic acids have hydrogen group of the acid COOH moiety removed. Among the preferred aroyl groups is benzoyl.
During the course of the reaction the various functional groups such as the free carboxylic acid or hydroxy groups will be protected via conventional hydrolyzable ester or ether protecting groups. As used herein the term xe2x80x9chydrolyzable ester or ether protecting groupsxe2x80x9d designates any ester or ether conventionally used for protecting carboxylic acids or alcohols which can be hydrolyzed to yield the respective hydroxyl or carboxyl group. Exemplary ester groups useful for those purposes are those in which the acyl moieties are derived from a lower alkanoic, aryl lower alkanoic, or lower alkane dicarboxylic acid. Among the activated acids which can be utilized to form such groups are acid anhydrides, acid halides, preferably acid chlorides or acid bromides derived from aryl or lower alkanoic acids. Example of anhydrides are anhydrides derived from monocarboxylic acid such as acetic anhydride, benzoic acid anhydride, and lower alkane dicarboxylic acid anhydrides, e.g. succinic anhydride as well as chloro formates e.g. trichloro, ethylchloro formate being preferred. A suitable ether protecting group for alcohols are, for example, the tetrahydropyranyl ethers such as 4-methoxy-5,6-dihydroxy-2H-pyranyl ethers. Others are aroylmethylethers such as benzyl, benzhydryl or trityl ethers or xcex1-lower alkoxy lower alkyl ethers, for example, methoxymethyl or allylic ethers or alkyl silylethers such as trimethylsilylether.
The term xe2x80x9camino protecting groupxe2x80x9d designates any conventional amino protecting group which can be cleaved to yield the free amino group. The preferred protecting groups are the conventional amino protecting groups utilized in peptide synthesis. Especially preferred are those amino protecting groups which are cleavable under mildly acidic conditions from about pH 2.0 to 3. Particularly preferred amino protecting groups are tertiary lower alkyl, lower alkyl and triloweralkyl methyl ether groups.
The heteroaromatic ring defined by R or R4 can be an unsubstituted or mono-substituted five- or six-membered heteroaromatic ring having from 1 to 3 heteroatoms selected from the group consisting of oxygen, nitrogen or sulfur. The heteroaromatic ring defined by R and R4 are connected to the remainder of the compound of formula I by a ring carbon atom. The heteroaromatic ring which is defined by R4 contains a first nitrogen heteroatom adjacent to the connecting ring carbon atom and if present, the other heteroatoms can be sulfur, oxygen or nitrogen. Such heteroaromatic rings include, for example, pyrazinyl, pyridazinyl, isoxazolyl, isothiazolyl, and pyrazolyl. On the other hand, when R is a heteroaromatic ring, this ring need not contain a nitrogen heteroatom. Among the preferred heteroaromatic rings are included pyridinyl, pyrimidinyl, thiazolyl, and imidazolyl. These heteroaromatic rings which constitute R or R4 are connected via a ring carbon atom to the remainder of formula I. The ring carbon atom of the heteroaromatic ring which is connected via the amide linkage to form the compound of formula I is not substituted with any substituent.
R4 is an unsubstituted or mono-substituted five- or six-membered heteroaromatic ring containing from 1 to 3 hetero atoms selected from the group consisting of nitrogen, oxygen or sulfur with one hetero atom being nitrogen and connected to the remainder of the molecule by a ring carbon atom. In this case, the preferred rings are those which contain a nitrogen heteroatom adjacent to the connecting ring carbon. The preferred five-membered heteroaromatic rings contain 2 or 3 heteroatoms with thiazolyl, imidazolyl, oxazolyl and thiadiazolyl being especially preferred. When the heteroaromatic ring is a six-membered heteroaromatic, the ring is connected by a ring carbon atom to the amine group shown, with one nitrogen heteroatom being adjacent to the connecting ring carbon atom. The preferred six-membered heteroaromatic rings include, for example, pyridinyl, pyrimidinyl, pyrazinyl, pyridazinyl, and triazinyl.
The term xe2x80x9cpharmaceutically acceptable saltsxe2x80x9d as used herein include any salt with both inorganic or organic pharmaceutically acceptable acids such as hydrochloric acid, hydrobromic acid, nitric acid, sulfuric acid, phosphoric acid, citric acid, formic acid, maleic acid, acetic acid, succinic acid, tartaric acid, methanesulfonic acid, para-toluene sulfonic acid and the like. The term xe2x80x9cpharmaceutically acceptable saltsxe2x80x9d also includes any pharmaceutically acceptable base salt such as amine salts, trialkyl amine salts and the like. Such salts can be formed quite readily by those skilled in the art using standard techniques.
In accordance with the present invention, preferable residue R3 is cyclopentyl. Preferable residue R4 is thiazolyl, optionally mono-substituted by xe2x80x94(CH2)mxe2x80x94C(O)OR7, wherein R7 is lower alkyl and m is 0, 1, 2, 3 or 4, preferably 0. Most preferable residue R3 is unsubstituted thiazolyl. Preferable residue R is selected from hydrogen; hydroxy lower alkyl such as hydroxy methyl, 2-hydroxy propyl and 2-hydroxy-2-butyl; lower alkoxy lower alkyl such as methoxymethyl; hydroxy substituted cyclohexyl; morpholino; unsubstituted pyridyl or pyrimidinyl; and xe2x80x94N(R1,R2), wherein R1 and R2 each independently denote a lower alkyl residue, preferably methyl, and n in the compound of formula I is 1 or 2, preferably 1.
The preferred compounds of formula I are those compounds where R3 is cyclopentyl (compounds of formula IA). Among the embodiments of compounds of formula IA are those compounds which R4 is an unsubstituted or mono-substituted 5-membered heteroaromatic ring. An embodiment of this invention where R4 is an unsubstituted or mono-substituted 5-membered heteroaromatic ring are those compounds where R4 is an unsubstituted or mono-substituted thiazolyl ring (compound of formula IA-1) with the unsubstituted thiazoles being designated compounds IA-1a and the substituted thiazole being designated IA-1b. Among the embodiments compounds of formulas IA-1a and IA-1b are those compounds where R is hydrogen or lower alkyl, and compounds where R is hydroxy lower alkyl or lower alkoxy lower alkyl Among the embodiments of the compound of formula IA-1b are those compounds where R4 is thiazole mono-substituted with 
and m and R7 are as above and R is hydroxy lower alkyl.
In accordance with another embodiment of compounds of formulas IA-1a and IA-1b are those compounds where R is 
and R1 and R2 are as above (the compound of formula IA-1a(1) and formula IA-1b(2)).
Among the embodiments of the compounds of formula IA-1 a where R4 is an unsubstituted thiazole are those compounds where; i) R is hydroxy substituted or unsubstituted cycloalkyl ring containing from 5 to 6 carbon atoms, a five- or six-membered saturated heterocyclic ring containing from 1 to 2 hetero ring atoms selected from the group consisting of sulfur, oxygen or nitrogen or ii) an unsubstituted five- or six-membered heterocyclic ring containing from 1 to 3 heteroatoms in the ring selected from the group consisting of sulfur, nitrogen or oxygen and n is 0 or 1.
In accordance with this invention, the compounds of formula I are produced by the following reaction scheme: 
wherein n, R, R2, R3 and R4 are as above, and R7 forms a hydrolyzable ester protecting group.
In accordance with this method, the compound of formula V is converted into the compound of formula VI by protecting the carboxylic acid group in the compound of formula V through the formation of a suitable hydrolyzable ester group. Any conventional hydrolyzable ester protecting group can be utilized in this conversion. In fact, in accordance with the preferred embodiment of this invention, the compound of formula V is reacted with methyl alcohol in the presence of sulfuric acid to form the methyl ester of the compound of formula V which methyl ester is the compound of formula VI. In the next step of the reaction, the compound of formula VI is reacted with the halide shown to form the compound of formula VII. This reaction is carried out utilizing conventional akylation techniques. Any conventional method of alkylating the alpha carbon atom of an organic acid ester with an alkyl halide can be utilized to effect this conversion and produce the compound of formula VII. In the next step of the reaction, the compound of formula VII is coupled with the alkyne of formula VIII to produce the compound of formula IX. Any conventional method of coupling an alkyne to an aromatic iodide can be utilized to effect this conversion. In accordance with the preferred embodiment of this invention, the coupling is carried out in the presence of copper iodide catalyst utilizing an auxiliary catalyst at temperatures of from about 80xc2x0 to 120xc2x0 C. Any coupling catalyst system can be used with the preferred system being bis-triphenyl phosphine dichloro palladium and copper iodide. After coupling, the compound of formula IX is converted to the compound of formula X by hydrolyzing the R7 protecting group from the compound of formula IX. Any conventional method of hydrolyzing an ester can be utilized to effect this conversion. In the next step of the process, the compound of formula X is condensed to the compound of formula XI to produce the compound of formula I. This condensing reaction can be carried out utilizing any of the conventional means of amide formation.
The compound of formula I has an asymmetric carbon atom through which the group xe2x80x94CH2R3 and the acid amide substituents are connected. In accordance with this invention, the preferred stereoconfiguration of this group is R.
If it is desired to produce the R or the S isomer of the compound of formula I, this compound can be separated into these isomers by any conventional chemical means. Among the preferred chemical means is to react the compound of formula X with an optically active base. Any conventional optically active base can be utilized to carry out this resolution. Among the preferred optically active bases are the optically active amine bases such as alpha-methylbenzylamine, quinine, dehydroabietylamine and alpha-methylnaphthylamine. Any of the conventional techniques utilized in resolving organic acids with optically active organic amine bases can be utilized in carrying out this reaction.
In the resolution step, the compound of formula X is reacted with the optically active base in an inert organic solvent medium to produce salts of the optically active amine with both the R and S isomers of the compound of formula X. In the formation of these salts, temperatures and pressure are not critical and the salt formation can take place at room temperature and atmospheric pressure. The R and S salts can be separated by any conventional method such as fractional crystallization. After crystallization, each of the salts can be converted to the respective compounds of formula X in the R and S configuration by hydrolysis with an acid. Among the preferred acids are dilute aqueous acids, i.e., from about 0.001N to 2N aqueous acids, such as aqueous sulfuric or aqueous hydrochloric acid. The configuration of formula X which is produced by this method of resolution is carried out throughout the entire reaction scheme to produce the desired R or S isomer of formula I. The separation of R and S isomers can also be achieved using an enzymatic ester hydrolysis of any lower alkyl esters corresponding to the compound of the formula X (see for example, Ahmar, M.; Girard, C.; Bloch, R, Tetrahedron Lett, 1989, 7053), which results in the formation of corresponding chiral acid and chiral ester. The ester and the acid can be separated by any conventional method of separating an acid from an ester. The preferred method of resolution of racemates of the compounds of the formula X is via the formation of corresponding diastereomeric esters or amides. These diastereomeric esters or amides can be prepared by coupling the carboxylic acids of the formula X with a chiral alcohol, or a chiral amine. This reaction can be carried out using any conventional method of coupling a carboxylic acid with an alcohol or an amine. The corresponding diastereomers of compounds of the formula X can then be separated using any conventional separation methods. The resulting pure diastereomeric esters or amides can then be hydrolyzed to yield the corresponding pure R or S isomers. The hydrolysis reaction can be carried out using conventional known methods to hydrolyze an ester or an amide without racemization.
All of the compounds of formula I which include the compounds set forth in the Examples, activated glucokinase in vitro by the procedure of Example A. In this manner, they increase the flux of glucose metabolism which causes increased insulin secretion. Therefore, the compounds of formula I are glucokinase activators useful for increasing insulin secretion.
On the basis of their capability of activating glucokinase, the compounds of above formula I can be used as medicaments for the treatment of type II diabetes. Therefore, as mentioned earlier, medicaments containing a compound of formula I are also an object of the present invention, as is a process for the manufacture of such medicaments, which process comprises bringing one or more compounds of formula I and, if desired, one or more other therapeutically valuable substances into a galenical administration form, e.g. by combining a compound of formula I with a pharmaceutically acceptable carrier and/or adjuvant.
The pharmaceutical compositions may be administered orally, for example in the form of tablets, coated tablets, dragxc3xa9es, hard or soft gelatine capsules, solutions, emulsions or suspensions. Administration can also be carried out rectally, for example using suppositories; locally or percutaneously, for example using ointments, creams, gels or solutions; or parenterally, e.g. intravenously, intramuscularly, subcutaneously, intrathecally or transdermally, using for example injectable solutions. Furthermore, administration can be carried out sublingually or as an aerosol, for example in the form of a spray. For the preparation of tablets, coated tablets, dragxc3xa9es or hard gelatine capsules the compounds of the present invention may be admixed with pharmaceutically inert, inorganic or organic excipients. Examples of suitable excipients for tablets, dragees or hard gelatine capsules include lactose, maize starch or derivatives thereof, talc or stearic acid or salts thereof. Suitable excipients for use with soft gelatine capsules include for example vegetable oils, waxes, fats, semi-solid or liquid polyols etc.; according to the nature of the active ingredients it may however be the case that no excipient is needed at all for soft gelatine capsules. For the preparation of solutions and syrups, excipients which may be used include for example water, polyols, saccharose, invert sugar and glucose. For injectable solutions, excipients which may be used include for example water, alcohols, polyols, glycerine, and vegetable oils. For suppositories, and local or percutaneous application, excipients which may be used include for example natural or hardened oils, waxes, fats and semi-solid or liquid polyols. The pharmaceutical compositions may also contain preserving agents, solubilising agents, stabilising agents, wetting agents, emulsifiers, sweeteners, colorants, odorants, salts for the variation of osmotic pressure, buffers, coating agents or antioxidants. As mentioned earlier, they may also contain other therapeutically valuable agents. It is a prerequisite that all adjuvants used in the manufacture of the preparations are non-toxic.
Preferred forms of use are intravenous, intramuscular or oral administration, most preferred is oral administration. The dosages in which the compounds of formula (I) are administered in effective amounts depend on the nature of the specific active ingredient, the age and the requirements of the patient and the mode of application. In general, dosages of about 1-100 mg/kg body weight per day come into consideration.
This invention will be better understood from the following examples, which are for purposes of illustration and are not intended to limit the invention defined in the claims which follow thereafter.